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  3. The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to resu

The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to resu

admin2014-12-26  74
问题     The complications frequently accompanying diabetes, such as impairment of vision and of kidney function, are now thought to result from the lack of continuous control of blood glucose concentrations. The healthy pancreas, in response to increases in blood glucose concentration, releases small quantities of insulin throughout the day and thereby maintains the concentration within physiological limits(nomoglycemia). But the diabetic generally receives only one large dose daily. The diabetic’ s blood glucose concentration can thus fluctuate greatly during the interval between doses, and it has been suggested that the complication result from the periods of high concentrations of blood glucose(hyperglycemia). Many investigators thus believe that restoration of normoglycemia might halt the progression of such complications and perhaps even reverse them.
    There are three primary techniques that have been investigated for restoration of normoglycemia. They are: transplantation of whole, healthy pancreases; transplantation of islets of Langerthan, that portion of the pancreas that actually secretes insulin, and implantation of artificial pancreases. There has, in fact been a great deal of success in the development of these techniques and each seems, on the whole, promising. Nonetheless, it will undoubtedly be many years before any one of them is accepted as a treatment for diabetes.
    To many people, the obvious approach would seem to be simply to transplant pancreases from cadavers in the same manner that kidneys and other organs are routinely transplanted. That was the rationale in 1966 when the first recorded pancreas was performed. Between 1960 and 1975, there were forty-six pancreas transplants in forty-five other patients in the United States and five other countries. But only one of these patients is still alive with a functioning graft and surgeons have found that the procedure is not simple as they once thought.
    The surviving patient has required no insulin since the operation. Another patient survived 638 days without requiring insulin. And one patient survived a transplantation for more than a year, but died when he chose not to take immunosuppressive drugs. These results, though meagre, suggest that the procedure has the potential for success.
    The rest of the patients, however, either rejected the transplant or died within a short period. There does not appear to be any technical problem with the procedure. Rather, most of the patients were already so severely debilitated by the complications of diabetes that they could not withstand the surgery and the immunosuppressive regimen required to prevent rejection. More than half of the patients, furthermore, also required a kidney transplant. Most investigators now agree that the simultaneous transplantation of both organs is too great a shock to the patient and greatly increases the total risk.
It can be inferred from the text that one of the important contributing causes of the failure of most pancreas transplants has been the______.
选项 A、reluctance of patients to cooperate with physicians
B、imperfect techniques used in the operation
C、scarcity of immunosuppressive drugs
D、weakened condition of the patients
答案D
解析 细节题。根据failure of most pancreas transplants定位到第五段Rather，most of the patients were already so severely debilitated by the complications of diabetesthat they could not withstand the surgery and the immunosuppressive regimen requiredto prevent rejection。“不过，大多数的病人都由于糖尿病的并发病已经很衰弱，以至于无法经受手术和为防止排异反应所需的免疫抑制疗程。”可知大多数胰腺移植手术的失败原因在于病人衰弱的身体，和选项D的表述一致。所以答案选D。
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